Automatic traffic control system



Aug. Z7, 1940. P. P. HoRNl AUTOMATIC TRAFFIC GON-TROL SYSTEM 4Sheets-Sheet l Filed Sept. 25, 1950 A N E .MSS

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tu Pfl-hue www D( ON mmol u mgm QN NEN ATTORNEY 5 Aug. 27, 1940, PLP.HoRNl AUTOMATIC TRAFFIC CONTROL SYSTEM Filed Sept. 25, 193D 4Sheets-Sheet 3 www Sw K n www SSN @QN www ATTORNEYS v Aug. 27, 1,940. p,HO'RNl I 2,212,985

AUTOMATIC TRAFFIC CONTROL SYSTEM Filed Sept. 25, 1930 4 Sheets-Sheet 4ff@ v INVENTOR ATTORNEYS A Patented Aug. 27,

UNITED STATES PATENT GFFICE 2,212,985 AUToMATrC Teams comer. SYSTEM Paninumana las; Application September 25, i930, Serial No. 484,334 t claims.(ci. rarsari This invention relates to an automatic traffic controlsystem of the type whose signals are subiect to control by the tramo.

Among the traffic control systems in use here-v tofore, a motor drivencommutator or circuit- -breaker operated continuously to ash the traillclights on and off to procure the successive signal cycles, whether ornot the traiiic was such as to warrant continuous control. Usually agreat deal lmore traillc traverses one street than the `otherintersecting street, but with the usual continuous. trai'c signal theheavy traffic traversing one street must stop periodically even whenthere is no cross-traino requiring such action, thereby li causingunnecessary retardation of traillc, which `would move more rapidly ifthe traiiic signal did not interfere with it unnecessarily. Accordingly,

a continuous trafilc signal system, though warranted by a certain amountof cross-traine -at times such as during the rush hours, does more harmthan good in such a case.

In many communities, in order to economize on power and save theequipment, it has become l the practice to shut oil' the continuoustrafc control equipment during the hours between midnight and earlymorning when trailic is very light, but because night drivers usuallytravel at high speed, the control -of traffic becomes more necessary atnight than during the day time, when the roads are not as free of traicas to permit high speed operation of vehicles. Accordingly, since thethoroughfares are without any trailic control whatever, because of thecustom .of shutting the tramo lights of! late at night, a dangeroustraiiic condition exists and many fatal accidents have occurred for thisreason. Such a practice would not be necessary if the tramo system werenormally inactive or dormant except at a time when converging orintersecting traillc made it 404 necessary. whether late at night orduring the day, whereby the system would itself economize on power,extend the life of the lamps, reduce servicing, and save the equipmentagainst wearing out rapidly due to continuous use.

Also in the instance where a continuously operating traillc signal islocated at an intersection where the cross-traillc is lighter than issuilicient to warrant the continuous signal, a vehicle operator, uponseeing the green light ahead whue '50 still a considerable distance fromthe intersection, races to cross the intersection before the signalilashes against him, which he would not do if there were no traiiicsignal ahead of him. This is a source of considerable danger and mightbe largely. avoided ii the traillc signal were only employed when thecross trame warrants it, i. e. a discretionary tramo control initiatedupon command, such as by a traiiic'omcer. is desirable.

It is accordingly the principal object of this invention to provide anautomatic trame signal g control system whose operation isinitiated'only upon command to dispose of whatever crosstraillc theremay be atany one time, andv thereafter lapses into inactivity to permitthe usual or heavy traiiic to ilowunimpeded until such timel0 that thereis cross-traiilc which requires control of the intersection. Thissystem. while fully mechanical in operation, is discretionaryin functionin that it only operates when" traiiic conditions make traic controlnecessary, whereby the l# enumerated objections to traillc controlsystems employed heretofore are obviated. By means of this new system,trailic is -expedited and not hindered when there is no reason forstopping it, and the thoroughfares and `theirI intersections 20 aresubject to -trailic control throughout the twenty-four hours of everyday, whereby traillc is dispatched safely stall times and all of thetime without excessive use of power and the equipment since` the systemonly operates upon coml mand when cross or convergent traiilc requiresits operation. In fact, very much less power is used than by thecontinuous cycle tramo equipment, less servicing 'and repair work isneeded, and the life of the lamps is extended. as 1s the me of the 3equipment as a whole.

- Another object of this invention is to provide an automatic traillccontrol system which is entirely self-contained and is provided with itsown local 35 battery, so that the system may be installed in outlyingdistricts where outside power is not readily available. Furthermore, thesystem may be installed without the necessity of making arrangementswith the power companies or running power. lines. often fromconsiderable distances, to the intersection where the system isinstalled.

Another object of this invention is to provide I a system of the typedescribed in which a complete signai cycle for controlling both the mainhighway and the cross street tramo is initiated by a vehicle orpedestrian approaching the intery section from the cross street. andthis cycle of operations may be extended a predetermined 56 number oftimes by additional impulses caused by successive vehicles orpedestrians until a predetermined time interval has elapsed, whereuponthe signals are restored to dispatch the main highway trameuntilanothersignal cycle is com- 55 pleted when anotherl cross travelingvehicle` or pedestrian can again initiate the signal cycle.

Another object of this invention is to provide a signal system of thetype described in which a vehicle seeking to negotiate a turn from oneor" the streets of the intersection in a signal zone either appropriatesthe signals to his benefit from other vehicles which are under thecontrol of the signals at that time or else initiates signals, if thesignal system is not otherwise in operation, whereby other vehicles atthe intersection are stopped until the turn has been completed by thevehicle who initiated or appropriated the signals.

A further object of this invention is to provide means along theroadside at a suicient distance ahead of the intersection underautomatic traffic control to warn approaching vehicles that they areentering an automatic signal zone and must be prepared for a. change insignal, if signals are being shown, or prepared for the initiation ofsignals if none are shown.

These and other objects of this invention are realized in a preferredembodiment thereof, comprising a local battery which supplies current tothe signal operating mechanism and the signal lights, this battery andthe signal mechanism being conveniently located adjacent theintersection in any suitable way and no outside power is required foroperation of the signal system. Placed in the surface of the crossstreet adjacent the intersection, in the sidewalk or otherwise adjacentthe curb at opposite sides of the main highway at the intersection, andin some instances in the center of the main highway on the right-handside of the same approaching the intersection, arecontact means wherebythe Weight of an object closes an electrical circuit to initiate theoperation of signal system or alter the operation thereof. 'I'he iirstcontact means mentioned, i. e., those located in the surface of thecross street adjacent the intersection, are subject to operation by theweight of a vehicle approaching the intersection on the cross streetfrom either direction; the second contact means, i. e., those placed onthe sidewall: or adjacent the curb on opposite sides of the mainhighway, are adapted to be operated by the weight of a pedestrianseeking to cross the main highway whose traffic is normally* unimpededby traffic lights; and the third contact means mentioned, i. e., thoseplaced in the middle of the main highway adjacent the intersection areadapted to be operated by a vehicle seeking to negotiate a left turnfrom the main highway into the cross street. Any one, any two, or allthree of these arrangements may be used in conjunction with each other,and in order to illustrate preferred arrangements of the invention Ihave described the combination of the cross street vehicle andpedestrian control as a complete system and also a cross street vehicle,pedestrian and left turn vehicle control as another separate andcomplete system.

Let it be assumed that a vehicle is approaching the intersection from across street with due care, having been warned several hundred feetahead of the intersection that he is approaching the zone of automaticsignal control. If no other vehicle has immediately preceded the vehiclein question toward the intersection along the cross street, the mainhighway tralc is traveling without interruption by the trac lights, asthe traffic lights are not illuminated in this instance. As the crosstraveling vehicle nearly reaches the intersection, the weight thereofcloses the street aaiaaes contacts and the signal cycle is initiated bya series of steps which includes the starting of an electric motorwhich, by a series of cam controlled contacts, performs the successiveoperations necessary to complete the normal signal cycle which involvesdashing the red, green and amber lights in proper succession againstboth the main highway traiic and the cross traveling Vehicle that hasinitiated the signal cycle. It will be apparent from `this discussionthat the main highway traic is stopped until the cross traveling vehiclehas crossed the main highway and proceeded on its way, after which timethe signal lights are again extinguished and the normal main highwaytraic proceeds in the usual uninterrupted manner.

As mentioned above, means are also provided for permitting a pedestrianto control the traiiic at the intersection if he seeks to cross the mainhighway. Of course he can freely cross the cross street, as it isassumed that the traffic thereon is not as dense as main highwaytraiilc. Accordingly, if a pedestrian seeks to cross the main highway,he steps upon one of the pedestrians contacts on the sidewalk orotherwise adjacent the curb at an intersection at a position so that hecan cross the main highway. The weight of the pedestrian operates thiscontact and the signal cycle just described in connection with the crosstraic is initiated and when the red light is ashed against the mainhighway traffic and the cross street green lights are lighted, thepedestrian may safely cross the street, the time interval beingsufficient to permit him to do so without danger. If a second pedestrianimmediately following the first one steps on any one of the fourpedestrians' buttons placed at the four corners of the intersection, thesignal cycle is delayed so that the cross street green light and themain highway red light remain energized for a longer period. 'Ihis timecan be extended by the successive operation of any one of thepedestrians buttons by four successive pedestrians, each of which tendsto slow up the signal motor a longer time until the predeterminedmaximum time has elapsed, whereupon the signals are restored to theirinitial condition.

Means may also be provided for permitting a vehicle to make a left turnfrom the main highway into the cross street whether or not the signalcycle is in operation, either from initiation by a cross travelingvehicle or by a pedestrian seeking to cross the main highway. It is onlynecessary for the vehicle which seeks to negotiate a left turn to pullup to the center of the main highway adjacent the intersection,whereupon the weight of the vehicle closes the contacts to eitherinitiate a new signal cycle or to interrupt the normal signal cyclewhich may be in operation at that time. The eiect of this interruptionor new initiation of the signal cycle is to stop all cross traili'c andmain highway trailc, except that in the direction from which the leftturning vehicle seeks to turn into the cross street, and a separatemotor is provided whose function is to control the signals in such a waythat a predetermined period of time is allowed the left turning vehicleto negotiate the turn from the main highway into the cross street. Afterthis special signal cycle has been completed, the signals are restoredto their initial position, unless intervening circumstances such asmentioned above change them. It wi be seen that the left turning vehicletakes precedence, and this is desirable in order to clear the mainhighway of left turning vehicles immediately, as they otherwise obstructtraffic and retard normal ow of main highway tramo.`

Other details of the invention will become apparent in the followingdescription of preferred embodiments thereof .which constitute completesignal systems which are automatically operated vby the traiiic only.under such circumstances when the operation is required by trafcconditions as otherwise the mechanism does not operate and its length oflife is increased, its consumption of power is small, and by providing aself-contained system it is admirably suited for controlling trafiic inoutlying districts or in such portions wherethe main highway trafficgreatly exceeds cross trafc, whereby no signals are normally. requiredfor. main highway traic except where infrequent cross trame appears.

For a better understanding of the invention, reference is made to theaccompanying drawings, in which Figure l is a schematic electricaldiagram of the automatic ltrahie control system of thisinvention;

tation of the traffic control system of this invention modified toinclude left-turning traffic control;

Fig. 3 is a diagram of a road or street intersection equipped with thenew control system, showing the arrangement of the vehicle'and thedpedestrian contact;

Fig. 4 is a similar diagram including curb indicators for warning theoperator of a vehicle that he is approaching a zone of traffic control;

and

Fig, 5 illustrates in enlarged detail the curb warning indicators.

In the arrangement of this invention, the traffic light housing II) ismounted in the center of the intersection of the cross'street with themain highway in the usual wayas shown in Figs. 3 and 4. Along the curbon either side of both the cross street and main highway are placed thewarning indicators II and I2 which are placed several hundred feet aheadof the intersection and are reflectors, lights, or are otherwisearbitrarily arranged or inscribed with warning legend to inform anapproaching vehicleoperator that he is approaching a zone of automaticsignal y control, and that ne must `be watchful of signals. If thesignals are inoperation because they were initiated by a cross-travelingvehicle, the approaching vehicle can observe the lights, but theindicatorsl and I I additionally warn him that the signal control isautomatic.

The operating mechanism, other than the lights I0, the warningindicators Il and I2, and the pedestrianand vehicle-controlled contacts,is placed in a suitable housing, and the battery which feeds themechanism may also be placed in the same oradjacent housing, wherebyboth the mechanism and the battery are readily accessible forinspection, repair and replacement,

Referring to the diagram of Fig. 1, it will be seen-that in the surfaceof the cross street in the path of 'traic approaching the intersectionfrom either direction are placed the vehicle controlled contacts 23 and23. These contacts may be simply a treadle which is depressed by theweight 1 f f the vehicle to connect the contacts electrically or it mayconsist of a diaphragm which, when depressed, moves a column of liquidto close' a,

' and return through wire 26 to battery.

' are Open.

remote switch, or to operate lever or gear systems for the same purpose,and the like, it being understood that any' equivalent arrangement willserve the purpose, i. e., that of closing a switch when a vehicle comesto rest at the proper point on the cross-street.

Assuming that a vehicle on the cross-street is approaching theintersection from the north. If no vehicle immediately ahead has justnegotiated the intersection from the cross-street, no traffic lights arevisible and the main highway traic flows uninterrupted by traffic lightsor cross traffic, the object being to dispatch the main' highway traicas quickly as possible. Several hundred feet before the approachingcross-street vehicle reaches the intersection, the operator thereof iswarned that he Ais entering a zone of automatic signal control by thewarning indicators I I and I2, shown in Figs. 4 and 5, and heeding thewarning the operator slows the vehicle down.

Cross-street vehicle trac control Referring to Fig. 1, as thecross-traveling vehicle nearly reaches the intersection the vehiclecloses street contact 23, and a' circuit is closed which is traceablefrom battery 2li,A closed line switch 2I, wire 22, contact 23, wire 24,relay 25 Relay 25 pulls down its armature 26 to close contacts` 21,which closes circuit from battery 26, wire 22, wire 28, contacts 21,armature 26, wire 29, separate wires 30 and 3l, which energize relays 32and 33, respectively, which are connected by wires 34 and 35,respectively, through wire 26 to battery 26.

Relayf32 pulls down its armature to connect contacts 31, thel armaturebeing locked in closed povsition by pawl 38. Similarly, relay 33 pullsdown its armature 39 to connect contacts 40, and the armature 39 islocked in closed position by pawl 4I.- Both relays 32 and 33 control thesame circuits, i. e., the two circuits of the motor A, the formercircuit being traced from battery 29, wire 22, wire 42, contacts 31,armature 36 of relay 32, wire 43, motor A, and wires 44, 34 and 26 tobatteryy2, while the latter circuit is traced from battery 20, wire 22,wire 45, contacts 46, armature 39 of relay 33, selector switch segment46, switch arm I1, switch contact I8, wire I9, the motor A, and wires48, 44, 34 and 26 tor battery 26.

As the motor begins to rotate, cam 50, mounted on cam shaft 5I, drivenby the motor A, drops its follower 52 olf its high point 53 to the nomotion 'surface which comprises the greater proportion thereof. Thisaction causes spring contacts 54 to close, which initiates thesignalling operation. At this time high point 59 of cam 60 has not movedits follower 58 and contacts 6I are closed. Also follower 66 lies in thenotch of cam 61 and contacts 11 are closed while contacts 68 As seenabove, wire 41 was energized by closed relay 32 when the cross streetvehicle contacts 23 were closed.' Therefore beginning with wire 41, acircuit may be traced through wire 55contacts 54, follower 52, wires 56,51 and 62, follower 58, contact 6I, wire 63, and terminal 64 where thecircuit divides. One branch thereof follows wire 14 red cross lights 15,wires 16, 34 and 26 back to battery 20, while the other branch circuitis completed from terminal 64, wire 65, follower 66, contact 11, wire19, amber main lights 18, wires 12, 13, 34 and 26 back to battery 26. Itwill be seen that the warning amber lights 18 are flashedto main highwaytrame, and the u red stop lights 15 to cross traic including the Vehiclewhich initiated the signals by closing street contacts 23 (or 23').

As cam shaft 5| rotatesfurther, follower 58 rides up on the high point59 of cam 60 and contacts 6| are opened, thus breaking the circuitpreviously traced to the main amber lights 18 and cross red lights 15and extinguishing them. Simultaneously, the follower of cam 90 drops inthe notch thereof, and closes contacts 86, thus closing a circuit fromenergized wire 41, wire 55, contacts 54, wires 56, 51 and 85. contacts86, to terminal |06 where the circuit divides,.one branch following wirei 01, solenoid |08 and wires 34 and 26 back to battery 20.Energization'of coil |08 withdraws locking pawl 38 and releases armature36 of relay 32 to break the circuit across contacts 31 and thru wire 41to a motor which was energized by the closing of street contacts 23 (or23') by the cross trafiic. The circuit to motor is maintained, however,through the parallel circuit closed by solenoid 33 from battery 20,Wires 22, 26, 45, contacts 40, closed by the armature 39 of relay 33,selector switch segment 46, switch arm I1, switch Contact I8, wire |9,motor, wires 48, 44, 13, 34 and 26 back to battery 20, so the motorkeeps on rotating.

It will be remembered that the circuit pre-1 viously traced upon closureof contacts 86 by cam 90 divided at terminal |06 and the remainingbranch may be traced through wires 81 and |09 to main red lights ||0,wires 12, 13, 34 and 26 back to battery 20. cordingly stop main highwaytraiic. Another division of this circuit may be traced from aforesaidterminal |06, wire 81, follower 8| of cam 80, closed contacts 84, wire II, cross street green lights ||`2, wires 16, 34 and 26 back to battery20. Thus cross traffic receives the go signal by its green lights ||2and main highway traiic simultaneously receives the stop signal by thered light |I0.

Next, the followers of cams 60 and 80 drop oi the high point thereof andclose contacts 6| and 83, respectively, and open contacts 84, the latteraction breaking the circuit to the cross green lights H2, while the main`red light remains lit. This new circuit is traced from energized wire41, wire 55, contacts 54, wires 56, 51 and 85, contacts 86, terminal|06, wire 81, contacts 83, terminal |20 where the circuit divides, Wire83, cross street amber lights 85', and wires 16, 34 and 26 to battery20. Thus the cross street green lights ||2 are extinguished and thecross street amber lights 85 are simultaneously lighted.

The other branch of the circuit just traced leads from terminal |20,through wire I2I, coil |22 and wire 26 back to battery. Vlnergization ofcoil |22 pulls pawl |24 away from ratchet |25 and causes the pawl |24 toknock pawl |69 also away from ratchet |25 to'permit spring |10 to returnthe step-by-step switch to its initial position so that its arm |1engages the initial contact I8. This restoring action is ineffectivewhen the step-by-step switch has not been actuated as is the case in thecircumstances described, but the switch has a function which will bedescribed later, and this is the manner in which it is restored afterperforming that function.

Now referring to the closure of contacts 6| by cam 60, this action takesplace an instant after the action of cam and elects the illumination ofcross red lights 15 and main amber lights 18. This circuit is traceablefrom wires 41 and 55, contacts 54, wires 56, 51 and 62, con- The redlights ||0 acof cam rides upon its no-motion surface and opens contacts86. The opening of contacts 86 breaks the circuit through the mainhighway red lights ||0 and the cross street amber lights 85, which hadbeen initiated by contacts B3 of cam 80. Opening of contacts 86 alsode-energized reset coil |08 of relay 32 so that it is ready for the nextsetting action. Immediately after the action just described the follower60 of cam 61 rides up on the no-motion surface of the cam to opencontacts 11 and close complementary contacts 68 to extinguish main amberlights 18 and illuminate green main lights 10, while cross red lights 15remain illuminated. Thus main highway traiic is restored and cross tracis stopped by the red lights 15 after having passed the car whichinitiated the signal action by closing crossstreet contacts 23 (or 23').Fig. l illustrates this condition of traffic control.

Meanwhile the motor continues to rotate until follower IDI of reset cam|00 drops into the notch |05 thereof to close contacts |02. The circuitthus established is traceable from battery 20, wires 22 and 45, contacts40 0f relay 33, wires 41 and 55, contacts 54, wires 56 and |04, contacts|02, and wires |03 to terminal II3, where the circuit divides, onebranch traversing reset coil ||4, and wires ||5 and 26 to battery 20,and the other'branch traversing wire ||1, reset coil II8, and wire ||9and 20 back to battery 20. The energization of solenoid I I4 pulls pawl4| from armature 39 to release it so that the connection betweencontacts 40 is broken thus deenergizing the entire system and the motorstops rotating and all lights are extinguished, main highway traiccontinuing without interruption as the signal system is controlled bythe cross trafiic. The follower 52 rides up on high point 53 of cam 50to disconnect contacts 54. The energization of solenoid ||8 has no eectunder traflic conditions just described and its function will bedescribed later.

Pedestrian trafic control Provision is also made for control of thetraic lights by pedestrians who desire to cross the main highway, which,it will be rememberedy if; normally open to trac at all times except vfa vehicle approaching from a cross street energizes the signallingsystem to stop the main highway traiic and permit the cross street tralcto cross the main highway. At opposite sides of the main highway at theintersection thereof with the cross street are placed the buttons |58,these buttons being preferably in the form of treadles upon which apedestrian steps in the act of crossing the street, and are placedeither on the curb, in the sidewalk adjacent the curb, or immediatelybelow the curb. The buttons or treadles may constitute a movable contactwhich is depressed by the weight of the pedestrian to bridge contactsI5| to close a circuit, which may be traced from battery 20, wires 22and |62, contacts |5| and |50, wires |53 and |54, contacts |55,normallybridged by the armature |56 of relay |51, wire |58, selector switchsolenoid |59, and Wires |60 and 26 lack to battery 20.

'I'he circuit just traced divides at terminal I6| and the other branchmay be traced from terminal |6|, wire |62, relay |63, and wire 26 backto battery 20. Relay |63 is the same type as relay I '1 0 beingsuiiicient to point outthat closure of relay |63 by lthe pedestriansbutton |50 holds down its amature |64 to bridge contacts |65. 'I'hisinitiates a circuit traceable from battery 20, wire 22, wire 20, relaycontacts |65, relay armatureV -1`5 |64, wires |66 and 29, relay 32, andwires 34 and 26 back to battery 20. Energization of relay 32 closesrelay contacts 31 to close the circuit to the motor A to start thesignal system into operation in the manner previously described. The se-120 quence of 'signals varies from amber to red on thesmain highway, andfrom red to amber to green on the cross' street, which is the signalcondition stopping the main highway traffic to permit the pedestrian tocross the main highway in safety.

It will be recalled that when the pedestrian stepped on one of thebuttons |50 solenoid |56 of the selector or step-by-step switch wasenergized, this action causing the armature |61 to be '30 pulledupwardly about its pivot |68. At the end of the armature |61 there is aspring pressed pawl |69 engaging the toothed pawl |25 carrying theswitch arm 1. Upward movement of the pawl causes ratchet |25 to rotateone notch against the tension of spring |10, so that contact arm I1moves from the first switch p oint I8 to the second switch point |26. Asthese two switch points are connected in parallel to the motor lead I9,this action has no effect on the motor A, and it keeps 40 running at thesame speed.

However, should a second pedestrian step on one of the vbuttons |50after the first pedestrian initiated the signal action, the sameoperation takes place, and the second energization of coil |59 againpulls armature |61 to cause pawl |69 to move ratchet |25 a second notchin a clockwise direction. This swings switch arm |1 from switch point|26 to switch point |1|, thereby cutting in a low resistance unit |1|into the circuit 4.50- of the motor A, thus causing the motor to slow ldown slightly to increase the cycle time, say five seconds, so -as topermit the second pedestrian to cross the main highway without danger ofthe signals initiated by the first pedestrian turn- 55, ing on him whenhe is partly across the main highway.

Should a third pedestrian step on one of the -buttons following thesecond pedestrian, coil t v|59 is again energized to advance the arm |1of 60 the step-by-step switch from point |1| to point |13, therebycutting in a second resistance unit |14 Ainto the motor A circuit toslow down the rotation of the motor still more, say another fiveseconds.

y Lastly, if a fourth pedestrian follows a third 7.5' had an opportunityof crossing the main highway in safety. Of course, many more pedestriansthan foui-` may cross, but four in succession is suflicient to start theselective trafllc control by pedestrians, and successively increase thesignalling time from say ten seconds to twenty-ve sec- ,5. onds or moreor less. Thus, the pedestrian traffic may not retard the main highwaytraffic for more than the predetermined time, so that the system isfool-proof, there being only sufiicient interruption of the main highwaytraiiic to per- 10 mit the safe passage of pedestrians for a period ofsay 10 to 25 secondsthis time, of course, being variable byproportioning the resistance units |12, |1I and |16 in a predeterminedratio to procure the desired slowing up of the signal opera- 1 tion.This may be done by making the resistance units adjustable in accordancewith common practice. t

It will be recalled Ithat when cam 80 closed contacts the completion ofthe cycle of signals 2 initiated by the cross trac, coil |22 wasenergized to pull pawl |24 away from the ratchet |25, this connectionalso knocking pawl |69 away from theratchet |25,A which is thus releasedso Athatl spring |10. is free to rotate the switch,-25 until switch armI1 again engages starting with point I8, and all of the resistance unitsare cut out of the motor 'circuit in readiness for the next startingoperation. It will also be recalled that at the time that con |22 'for'resetting thefto step-,by-step switch vwas energized, relay |51- wasalso energized, this action causing the armature |56 of the latter tobreak the circuit between the contacts |55, which also breaks thecircuit through the selector or step-by-sten switch solenoidy |59, sothat any further closing of the pedestrians buttons |50 would have noeffect on the system. When this took place, locking pawl |11 engagedarmature |56 to hold it-down after relay |51 was deenergized, so tha-tf'4 the breakin the circuit occasioned .by energization thereof wasmaintained. When the entire signalling cycle wascompleted', cam |00closed contacts |02 to, energize coil H6, which disengage pawl |11 fromarmature |56 of relay |51` 45 to reset the same in readiness for thenext operation. Y

Inprecisely the same way that successive pedestrians may increase thesignal time, successive cross-traveling vehicles may increase theflength of the signal cycle by arranging the steel contacts 23 and 23 asthe pedestrians buttons |50 are arrangedI to operate the selectorswitch, or another one like it connected in parallel therewith, to cutresistances |12, |1l and |16 suc-- sively into the circuit ofl motor A,so that the signalcycle time is increased, say, ve successive vehicleswhich engage either contact 23 or 23. The idea and circuit arrangementis identical, so it is deemed suflicient to describe one of them for acomplete understanding of the other. This also applies to any othersignal by cycle such as that initiated'by a left-turning' vehicle in themanner to be described later in .o5 connection with Figs. 2 and 2a. y,

It will .be seen that the automatic signalling system illustrated inFig. 1 controlled indi-- vidualiy by the cross street traiic, or by thepedestrian trame, and that fit is only in operation when a vehicleapproaching f-rom the cross street or a pedestrian seeking to cross themain highway initiates the operation thereof, and that it is otherwiseout of operation because it is desirable to maintain main highway tramocontinuous when there is no cross traflic to interrupt it. It is wellknown that when intersections such as the one described are not equippedwith some kind of a signal system, or when the ordinary signal system ofalternately cyclic operation of the main highway and cross street lightsis employed, the main highway traflic is frequently needlessly stoppedat periodic intervals when their is no cross traiiic requiring suchaction.

Accordingly, the present invention provides for energization of thesignal system only when there is cross traffic requiring -the stoppageof the main highway tramo and at other times the main highway traiiicows continuously without interruption, and the signal lights are notilluminated at all. Thus, the apparatus of the present invention is onlyused when necessary, and facilitates tramo ow and eliminates the use ofthe expensive continuously operating traic systems or the servicesof anattendant or traic omcer.

Now, referring to Figs. 2 and 2a, which are complementary drawingsconstituting one complete schematic circuit, this arrangement goes astep further than the traillc control system described in connectionwith Fig. 1 in that provision is not only made for controlling thesignals by means of a cross street vehicle and pedestrians. but meansare also provided to permit a vehicle seeking to make a left turn intothe cross street from the main highway to appropriate to itself thesignals if already initiated by a pedestrian or cross-traveling vehicleand, if this is not the case, to initiate such signals as will stop alltramo interfering with the left turn so as to permit it to make the turnby energizing the appropriate signal lights.

In genera-l, the mechanism controlled by the pedestrians and the crossstreet traino is the same as that described in connection with Fig.

' which form elements of the additional mechanisin mentioned above. Forconvenience, however, the circuits common to both Figs. 1 and 2-2a willbe brieiiy traced, a cipher being added to the common referencecharacters of Fig. 1 in order to avoid confusion and yet enable thecommon elements of the two circuits to be compared most readily.

Assuming as before that a vehicle is approaching the intersection fromthe north on the cross street and that, a'tter having observed: thewarning indicators and |2 several hundred feet ahead of theintersection, he proceeds cautiously until he engages street contact 230(or 230'). From battery 200 the circuit may be traced to the cross tramevehicle contacts .230 (and 230') through closed switch 2|0, terminal2||, where the circuit divides, wire 220, terminal 2| 2 where thisbranch of the circuit divides again, one branch following wire 2|3,terminal 2M, wire 2li, terminal 2|6, wire 2|1, terminal 2|8, wire 2|9,wires |520, street contacts 230 and 230', wir |530, terminal |53i, wire240, solenoid 250, wire 260, terminal 26|, and wire 262 back to battery200.

Energization of solenoid 250 causes armature 250' to bridge contacts210, thus completing another branch circuit from terminal 2|6, wire 280,relay contacts 210, relay armature 250', wire 290, terminal 29| wherethe circuit divides, one branch including relay 330, which isaccordingly energized, and wires 350, 260, and 26| back to battery 200.The other branch of the last named circuit is traceable from terminal29| through wir@ 300,

relay 320, and wires 32| and 262 back to battery 200. Energization ofrelay 320 pulls down armature 360 to bridge contacts 310, thuscompleting the branch circuit from terminal 2|2, relay contacts 310,armature 360, wire 31|, terminal 312, 5 where the circuit divides, onebranch going to selective switch segment 460, wire 410, relay contacts41|, normally closed by the armature 412 of relay 413, wire 414 to motorA, and return t0 wires 440, terminal 44|, and wire '442, to battery 10200. When relay 320 was energized, its armature 360 locked in closedposition by the pawl 38|, which is releasable by coil |080 in the mannerto be described later. Similarly, the armature 29| of relay 330 isdropped in closed position by pawl 4|0, which is releasable by coil H40in a manner to be described later.

As the motor A begins to rotate, cam 500 drops its follower 520 off itshigh point 530 to the nomotion surface that comprises the greaterportion thereof. This action causes spring contacts 540 to close, whichinitiates the signalling operation. At this time, contacts 6|0 of cam600 are also closed, and contacts '|10 of cam 610 are closed, whilecontacts 680 are open. Contacts 540 are connected by wire 550 toenergized wire 414, mentioned above. This completes a circuit fromcontacts 540 through wire 560, wire 510, wire S20, contacts 6|0 of cam600, terminal 6|| where the circuit divides, one branch following wire630, wire 650, contacts 110, wire 190, both amber main highway lights180, and wires 1| 0, 120, and 442 back to ybattery 200. Thus the warningsignal is ashed on the main highway trailic which, in the absence of anycross tra-mc, is normally as iiowing without interruption from anysignal lights.

It will be recalled that the circuit just traced divided at terminal 6H,and the other branch follows wire 6| 2, back contacts 6|3, which arenormally closed by armature |4 of relay SI5, wire BIG, relay 6|1, whichis accordingly energized, and wires SIS and 262 back to battery 200.Energization of relay SI1 causes its armature 6|! to bridge its contacts62|. The closure of relay SI1 completes a circuit traceable from battery200, terminal 2H, wire 622, wire 623, armature 6|9, and contacts 62| ofrelay 6|1, where the circuit divides, one branch following wire $23 tosouth cross street red light 624, and wires 120 and 50 442 back tobattery 200, the other branch of the vcircuit following wire 625 tonorth cross street red light 626 and wires 120 and 442 back: to battery.200. Thus, in this condition, the signalling system for cross streettraffic is stopped by red 56 lights 624 and 626, and the amber lights180 are flashed on the main highway trailic.

The next action is causedby follower 580 riding up on the' high point590 of cam 600 to break the connection between contacts BID. This 60breaks the circuit to the main highway amber lights 180, which has justbeen traced, and also deenergizes relay SI1 so that its armature 6|! isreleased and is drawn upwardly by coil spring 621 to break theconnection between relay contact 82| and the circuit to cross street redlights $24 and 626. Accordingly, the main highway amber lights 180 andthe cross street red lights 624 and 626 are extinguished.

Simultaneously with this action, the follower of cam 900 drops into thenotch thereof and closes contacts 860, thus closing a circuit fromenergized wire 414, wire 550, contacts 540 of cam 500, wires 510 and850, contact 860 of cam 92B, to terminal 86|, where the circuit divides,one 75 light 102 and wires 1I0, 120 and 422 back to battery 200. Theother branch circuit may be traced from the other contact 694 of relay69| via wire 103 to terminal 104 to terminal 134, where the circuitagainst divides, one branch to open contact 105 of relay 106 and theother via wire 101, the west main green light 108, and wires 1I0, 120and 442 back to battery 200. Thus the main highway tralc is restored bythe simultaneous energization of main green lights 102 and 108.

As the motor A continues to rotate the fol-' lower of reset cam |000drops into the notch thereof and closes contacts |020, thus establishinga circuit which may be traced from wire 414, wire 550, contact 540 ofcam 500, wires 560, 510 and |040, contact |020 of cam |000, wire IO0I,terminal I 002 where the circuit divides, one through reset coil I |40,which disengages pawl 4I0 from armature 390 of relay 330 so thatcontacts 400 are again opened, the circuit being completed through wires|003, 260 and 262 to battery 200. The other branch of this circuit maybe traced from terminal |002, reset coil |004, and wires |008, 260 and262 to battery 200. Energization of reset coil |004 disengages pawl fromarmature |560 which again bridges contact |550 in readiness for the nextoperation. The signal system is now deenergized, and follower 520 ridesupon the high point 530 of cam 500 to separate contacts 540, thusbreaking the signal cycle initiating circuit and all signals areextinguished and main highway traiiic continues to flow uninterruptedly.

Left-turn signal control It will be observed that the operation of thecircuit illustrated with reference to Figs. 2 and 2a is so far similarto the apparatus illustrated by Fig. 1, the diiference being principallythe individual operation of the main and 'cross red and green lights bythe interruption of the double contact relays 699, 81|, SI1, 69|, 886,|93 and 413, in the first named arrangement, and whose function procuresno diierent results in ordinary traffic than the last named arrangement.These relays are, however, operative to procure a different combinationof signals when a vehicle on the main highway desires to make a leftturn into the cross street. ,For this purpose vehicle-controlledcontacts 2000 and 2000' are placed in the main highway adjacent thecenter thereof as shown in Fig. 3, the main highway still beingconsidered for convenience as running east and west and the cross streetas running north and south, the latter having the vehicle controlledsignal initiating contact 230 and 230 and the former havingthe'pedestrian-controlled buttons |500, whose operation and the controlof the signal cycle time being precisely the same as described inconnection with Fig. 1, and further description is accordingly notnecessary.

In operation of the left turn signal control, a vehicle about to enterthe signal zone from the west on the main highway, for example, anddesiring to execute a left-turn to the north into the cross street,draws to the center of the mainhighway stops and closes contacts 2000.It will be observed that vehicles seeking a right turn pass to the rightof the main highway and avoid contacts 2000. The circuit controllingaction of the latter is so arranged with a time lag, for example, as tobe unresponsive to the momentary weight of passing cars and isresponsive only to the weight of a car standing thereon.

Now referring to the circuit diagram of Figs. 2 and 2a, closure of leftturn contact 2000 initiates a circuit traceable from battery 200, wires220, 2I3,2I5,2I1 and 2I9, left turn contact 2000, wire 200|, relay 2002,and wires 2003, 260 and 262 back to battery 200. Energization of relay2002 pulls down its armature 2004 to bridge contacts 2005, the armaturebeing locked in this position by pawl 2006. This completes a circuittraced from battery 200, wires 220, 2|3, 2I5, 2I1, 2I9, and 2001, relaycontacts 2005, wire 2008, relay 2009, and wires 20I0, 260 and 262 backto battery 200. Relay 2009 pulls down one end of armature 20II, whih ispivoted at 20|2. This action causes contactors 20I3 and 20I4 to bridgecontacts 20I5 and 20I6, respectively, and the depressed end of armature20II is locked down by pawl 20|1.

Considering the effect of this bridging of contact 20I5 by contacts 20|3rst, the circuit is traceable from battery 200, wires 220, 2|3, 2I5 and2|1, terminal 2I8, wire 20|8 to contacter where the circuit divides, onebranch being traceable through wire 20I9, relay '|06 and wires 6I8 and262 back to battery 200, while the other branch is traceable from theother contact 20I5 of relay 2009, wire 2020, relay SI5 and wires 202|,6I8 and 262 back to battery 200. Energization of relay 106 causes itsarmature 2022 to bridge contacts 105, thereby closing a circuittraceable from battery 200, wire 622, relay armature 2022 where thecircuit'divides, one branch following wire 88|, east main red light 882,Wires 1I0, 120 and 442 back to battery, and the other branch istraceable from the other contact 105 of relay 106, wire 101, main westgreen light 108 and wires 1I0, 120 and 442 back to battery 200.

The aforementioned energization of relay SI5 caused armature 6I4 tobreak the normal connection between contact GIS and connect contact2023. Thiscompletes the circuit traceable from battery 200, wire 622,contacts 2023 of relay SI5, relay 6I1 and wires 6I8 and 262 back tobattery 200. Energization of relay SI1 causes its armature 6 I9 tobridge contacts 62|, thus completing a circuit traceable from battery200, wires 622 and 623, spring 621 and armature 6|9 of relay SI1 wherethe circuit divides, one branch following wire 623, south cross redlight 624 and wires and 442 back to battery 200, while the other branchfollows wire S25 from the other contact 62|, a relay 6I1, north crossred light 626 and wires 120 and 442 back to battery 200. Thus the leftturning vehicle entering the intersection along the main highway fromthe west engaged left turn contacts 2000 and initiated the signal cyclejust traced whereby it obtained its right of way into the north crossstreet, ashing the west main highway green light for the turn, the eastmain highwayred light against west moving traflic so that the turn mightbe completed and also stopped cross street traffic so that no crossmoving vehicles would interfere with its progress during the left turn.

It is lseen that this left turning vehicle immediately assumed controlof the traillc mechanism the moment it closed left turn road contacts2000 and it was enabled to take precedence over other traic, and this isdesirable because left turning vehicles by stopping in the .middle ofthe highways from which they seek to turn interrupt trailic which wouldotherwisebe dispatched without interruption and with greater rapidity soit is of advantage to get the left turning traffic out of the way assoon as possible. This approrelay 2009.

.nector 20|4 to bridge contacts 20|6. This closure of contacts 20|6 byconnector 20|4 establishes a 'I branch circuit which may be traced frombattery 200, wires 220, 2|3, 2|1, 20|8, contact 20|6, wire 204|, motor Band wires 32| and 262 .back to battery 200. 'Ihe motor rotates at aspeed sumcient to permit the left-turning vehicle to clear the othertramo and make the left turn.- This' time interval is determined by cam2032,

' and as soon as the follower 2042 drops into the notch 2043 thereof,contacts-203| are closed y and the left-turning signal control mechanismis reset. 'I'his resetting action may be followed by tracingtheotherbranch circuit for contact 20|6 of relay 2000 from battery 200, wires220, 2|3, 2|5, `and 2|1. terminal 2|`0, wire 20|0, connector 20|4,wire.2025, relay 2026 and wires 32| and 262 and back to battery 200.Energization of relay 202'0 causes its armature 2021 to bridgeA contacts2020, thus initiating a circuit traceable from 4battery 200, wiresA 220,2|3, 2023, which is not completed until normally open contacts 203| areclosedA at Ythe end of the cycle by cam 2032 which is driven by motor Bset in operation in the manner described. l

When follower 2042 of cam 2032 drops into the notch 2043 thereof,contacts 203| are closed and the -circuit is completed viawire 2033,contacts 2028 of relay 2026, wire 2034, terminal 2035 where thecircuit-divides, one branch energizing reset coil 2063 and.v beingcompleted through wires 2003, 260 and 262 back to battery 200, while theother branch from terminal 2035 fol- -lows wire 2030 to reset coil 2031,wires 2038,

260 and 262 back to battery. Energization oi' re` set coil 2003 pullspawl 2006 away from amature 2004 of relay 2002 and the connectionbetween contacts 2005 is broken, thus restoring the relay 2002 which wasenergized by the closure of the left turn main highway contacts 2000.'Iihe breaking of the connection between contacts 2000 of relay 2002de-energi'zes relay 2003 and the energizatlon of reset coil 2031 oi thislast named relay pulls pawl 20H away from armature 201| which is nowreleased to break the connection between connector 20H and contacts 20|5and between connector 2014 and contacts 20H6 of said The coil springs2033 restore armature 20|| to its normal position shown in Fig. 2. Alsoduring the time that the left turn signals are energized, whichisdetermined by cam-2032 since this cam resets the left turn signalmechanism, the initial connection of contacts 20|6 of relay 2000 byconnector 2014 energized relays 413-and |33, causing their respectivearmatures 412 and |32 to break connection between respective con-I Itwill be recalled that amature |02 normally completes one of the circuitsto master motor A and that this circuit is therefore broken while theleft. turn signal mechanism is in operation, and that amature 412 ofrelay 413 normally completes the other remaining circuit to theY mastermotor A vso that this circuit is also broken. Accordingly, while theleft turn signal mechanism is in operation, the master signal motor A isstationary and all normal signals remain in the particular energizedcondition which'they were in. when the left-turning vehicle closed mainhighway contacts ma. 'rnus the len aiming vehicle appropriat toitselfthe signals which are necessary to permit it to negotiate the desiredleft turn and in so doing it also stops traillc moving against thealternative circuits to the master motor A which controls the normalsignal cams. 0f

. course, ifl the normal signals are not in operation at the time thatthe left-turning vehicle engages street contacts 2000, the breaking ofthe circuit to motor A has no effect since the motor is not then inoperation.

Precisely the same signal place when the vehicle approaching` from theeast along the main highway moves to the center of the main highway andcloses contacts 2000' in the first movement toward making a left turn tothe south'into the cross street. .A different set of initiating elementsare provided but these elements are connected in parallel with thosecontrolled by left turn contacts 2000 and so: the cycle is exactly thesame. For example, closing of contacts 2000' initiates a circuittraceable from battery 200, wires 220,213, 2|5 and 2|1, terminal 2|8,wire 2|9, ieft turn contacts 2000", wire 2045, relay 2046 and wires2003, 260 and 262 appropriation takes back to battery 200. Relay2MB-corresponds to relay 2002 whose operation was described in derelay2046 effects completion of a circuit traced from battery 200, wires 220,2|3, 2|5, 211, 2|9 and 2001, contacts of relay 2046, relay 2041 and wire260 back to battery 200. Relay 2041 swings armaturev 20H around itspivot 20|2 to bridge the sets of contacts 2040 and 2049-. Bridging ofcontacts 2049 completes a circuit traceable from battery 200, toterminal 2|8, wire 20|0 to contacts 2049, where the circuit divides, onebranch being traceable through wire 2l I0, relay 603 backto battery 200,and the other branch following wire 2220 to relay 6|5 and back tobattery 200. Energization of relay 603 bridges contacts 690, therebyclosing a circuit from battery 200 to relay contacts 690, where thecircuit divides, one branch following wire 10|, east main green light102 and wire 120 back to battery 200, and the other branch follows wire016. west main red light 611 and wire back to battery 200.

The aforementioned energ'lzation of relay 6|5 causes armature 6|4 vtobreak the connection between contacts 6|3 and bridge contacts 2023. As

before, this causes energization of relay 6|1,`

which bridges contacts 62|. The circuit completed by relay 6|1 divides,and one branch follows wire 623 to south crossl red light 624 and backto'battery. while the other branch follows wire 625 to north cross redlight 626 and back to battery.

Y is lighted to start the vehiclev on its left turn, west main red light011 is lighted tostop westtravelling traflic, so that thelcft-turningvehicle may ,Y

moveV south into the cross street, and both cross street red lights 624and 026 are energized to stop cross tramo and permit the left-turningvehicle to complete its turn. The signal. cycle is restored as before. 1

Itis to be understood that each cross-travelling vehicle, pedestrian, orleft-turning vehicle which initiates or otherwise controls a signalcycle is considered as a single traiiic unit. Thus, a pedestrian seekingto cross the main highway, is like a cross-travelling vehicle, a unit oftrafiic, and if more than one vehicle or pedestrian Should engage acorresponding street or side-walk treadle or contact at the same time,or treadles or contacts which are connected in parallel, the aggregateoi this signal initiating or controlling are considered as a singletraic unit. All following vehicles or pedestrians which reenergize thesystem after one cycle or reenergize the sei lector switch to increasethe time of the signal cycle, whether one or more vehicles orpedestrians at the same time or withina predetermined time limit so thattheir joint actions procure a single eiect, are all consideredsuccessive units of traic.

It is desirable to facilitate right turns to or from the main highwayinasmuch as no crossing of trafc is necessary when a- 'right turn isexecuted, and so the initiation or operation of the signal equipment isnot necessary. As mentioned above in connection with the left turn,vehicles seeking to execute a right turn draw toward the curb and soavoid the left turn 2G00 or E contact in the main highway, which isspaced from the curb, so that it is not actuated to initiate orappropriate the signals. Where the width of the cross street issuiiiclent topermit it, the cross street contacts '23E and E38' are alsopreferably spaced from the curb to allow the right-turning traiic toavoid it. In this arrange- A ment the cross street contacts 236 and 230resemble the left turn contacts 2060 and 2099' in position in thestreet. Of course, the cross street may be equipped with left turncontrol and if this is done, the right-turning traiilc willautomatically avoid the contact, which is spaced from the Curb.

In the arrangement illustrated in Figs. 3 and e, a left-turning vehiclecoming from the north actuates contact 23B, so that both main redlights, and both cross green lights are lighted in the manner described,thus permitting another left-turning vehicle coming from the south toexecute a left turn at the same time. f course, either the main highwayor the cross street or both may be equipped with both the straightwaycontacts Zil@ or 26ml' and the left turn contacts 225 and 23S', but asthis complicates the situation considerably, it would probably not ndmuch use except under exceptional circumstances.

The term left turn as employed herein, refers primarily to the manner ofturning from one tralc lane across another traic lane on the samestreet, as where an operator of a vehicle in traffic moving at theright-hand side of the street makes a left turn across the left-handside of the street.' However, in locaiities where it is the custom forvehicles to travel along the left-hand side ofthe street, as is the casein many foreign countries, the same kind of turn would be a right turn,and it is to be understood that for the purposes of this invention. theterm left turn used herein is synonymous with the term right turn incases where traffic customarily travels on the left-hand side of thestreet.

The new invention provides many apparent advantages over the continuouscycle type of` traic control systems, in which a commutator or the likeuniformly controlled the signals in opposite directions, or a specialattendant or trac omcer was employed to throw aswitch from time totime'to regulate the trafhc in accordance with its density. Inconsidering these advantages, it should be emphasized that the system ofthis invention is normally dormant or inactive so that the main trafc inone direction or right turns at theA intersection are not interferedwith but allowed to flow freely with despatch. It is only when avehicle, pedestrian, or other traffic unit seeks to make a left turnfrom or to enter the traiiic stream from outside such as from a .side orcross street, other than by a right turn,

that the signal equipment is energized and the operation of the signalcycle initiated.

It is to be understood however that the term intersection does notnecessarily mean the intersection, crossing or mergence of straightstreets, roads or thoroughfares, but broadly means the joining of two ormore traiiic lanes whether or not any of these lanes is straight. Forexample, a traic carrying lane may curve such as around a corner, whilethe intersecting lane may enter at the corner in the shape of a T. Inthis case either the angle lane or the intersecting lane maye be themain highway. Also, main highway does not necessarily mean a boulevard,main street, or the like, but a tralc lane which carries either more orheavier traiiic or traic whose dispatch is considered more important ordesirable for any reason, while cross street or side street means anytraiiic lane entering the traffic lane dened as the main highway,whether or not the trame traversing either is vehicular, pedestrian,railway, or the like. However, for convenience and clarity, a trafiiclane which passes entirely through an intersection, whether on thestraight-away, curve or angle, and which is formed by two alignedstreets across the intersection, is called a main highway or simplyhighway while a traffic lane which approaches and terminates on theintersection is called a street or cross-street. By the presentinvention a. complete system may be installed conveniently at anyintersection such as in outlying districts or along arterial highwayswhere the highway trailc density greatly exceeds that entering thehighway from the cross or side streets or crossing the same from thecross streets. Such intersections greatly outnumber those in whichtraffic is substantially uniform in cross directions; i. e., along themain highway and crossing or entering the main highway from cross orside streets. Accordingly, the control of the system by the relativelyfew vehicles entering or crossing the main highway from the cross orside streets, or by pedestrians seeking to cross the main highway,.or byvehicles seeking to make a left turn from the main highway into the sidestreet, is greatly to be desired, and the system of this invention isadapted to provide these requirements. l

Also by providing preindicating signals or arbitrary warning indicatorsalong the roadside several hundred feet ahead of the intersection fordefining the signal zone, vehicles are warned that they are approachinga zone of automatic signal control and should proceed withdue care,these arbitrary indicators being so designed as to mean just this t0 theoperator of a vehicle.

Furthermore, the system of this invention is entirely self-containedandis provided with its own local source of power for its operation so thatit may be installed anywhere Without regard to outside power facilities.inasmuch as the system only operates when cross traflic or ,left-turningtraic initiates .such operation, the mechanism is only in use a part ofthe whole day and is dormant for long intervals, especially at night,whereby depreciation because of excessive use and the expense caused byunnecessary power consumption is eliminated.

While a preferred embodiment of the invention has been illustrated anddescribed herein, it is to be understood that the invention is notlimited thereby but is susceptibleV of many changes in form and detailWithin its scope, and any one, any two', or all of the severalseparately operated and coordinated signal controlling arrangements maybeused at will so that the system of this invention may be adapted tosuit all requirements of automatic traic control.

I claim:

l. A tratlic control system for two substantially parallel and oppositetrailic lanes, comprising a stop signal for each lane, means so disposedas to be actuated only by a unit of traffic in one lane taking aposition to make a turn across the other lane and not by through traiiicin said one lane, and means to be actuated by saidtraic actuatable meanswhen said tramc actuatable -means is actuated to provide a stop signalfor said other lane.

2. A traiiic control system for the intersection of a cross-street witha highway, comprising an electrical tramo signal, a source oi powertherefor, switch'means in the circuit of said signal and said source forcontrolling the energization of said signal, timing mechanism foroperating said switch means. an electric motor whose speed is responsiveto the resistance of its circuit for driving said mechanism, anenergizing circuit for said motor, devices at said cross-street adjacentthe intersection operable by a traffic unit seeking to enter the highwayand operativelyl connected to saidmotor for controlling the same, anelectrical resistance in the circuit of said motor, and means actuatedby a second operation of said devices for varying said resistance,whereby the motor speed is varied to vary the length of time of thesignal cycle initiated by the first traffic unit.

3.l A traiiic control system for intersecting tramo highways, one ofsaid highways comprising a plurality of traiiic lanes for traiilc movingin one direction, a Go signal for one lane of said plurality o'f lanes,a Stop signal for the other of said intersecting highways, and tramoactuable means in said Go signal controllable lane actuable by a unit oftrailic in said'one lane taking a position to make a turn across aninterfering traiiic lane in other of `said intersecting highways toactuate lsaid stop signal.

4. A traic control system for intersecting tramchlghways, one of thehighways having a plurality of traic, lanes for traic moving in onedirection and at least one trafilc lane for traiiic moving insubstantially a parallel and opposite direction, comprising a stopsignal for each of the lanes andv a go signal for one of the pluralityof lanes moving in one direction, means so disposed as to be actuatedonly by a unit of traiiic in a preselected lane of the plurality oflanes moving in one direction taking a position to make a turn acrossthe lane moving in the opposite direction and not by through traffic inthe preselected lane, and means to be actuated by the trafc actuablemeans wherein said means is actuated to provide a stop" signal for theother lanes of tramo.

PAUL l?. HORNI.

